Electrophysiologic Principles of Radiofrequency Lesion Making

Abstract

Understanding of the electrophysiologic principles of radiofrequency lesion making is necessary to ensure reliable results in surgical procedures using this technique. A radiofrequency lesion is produced by tissue electrocoagulation. lts method of formation and factors affecting heat generation and loss are discussed. Guidelines for making radiofrequency lesions, based on electroph<X_Underline>ysiologic</X_Underline> principles, are outlined.

Technical Considerations in CT-Guided Radiofrequency Thermal Ablation of Osteoid Osteoma: Tricks of the Trade

“…Resistance of biologic structures causes local ions to vibrate. This ionic agitation results in friction around the electrode tip as ions attempt to pursue changes in direction of the alternating current and create heat to the point of dessication-hence, the term "thermal ablation" [12,13]. Radiofrequency thermal ablation differs from electrocautery in that the tissue around the electrode, rather than the electrode itself, is the primary source of heat (Fig.…”

“…The maximal size of the treatment zone may be predicted by the following equations: long axis of treatment zone = 2 × length of bare tip transverse axis = 2/3 long axis [13].…”

“…CT-guided radiofrequency thermal ablation should be attempted only when a definite nidus is identified on CT in a patient with an appropriate [13]) A, Drawing shows difference in current flow and heat flow in electrocautery with current through heater element in probe resulting in heat flow from probe to tissue (top) and radiofrequency thermal ablation with current flow into tissue resulting in heat flow from tissue to probe (bottom). B, Drawing shows side and front views of radiofrequency thermal ablation treatment zone, which is spherical ellipse centered on noninsulated portion of electrode tip.…”

“…Charring manifests as an abrupt fall in current with a voltage rise due to increased tissue resistance. Alternatively, areas of vaporization can result in an irregular-shaped zone that may be larger in parts, but with other areas that are not ablated [13] (Fig. 5).…”

The Response of the Slow Atrioventricular Nodal Pathway to Temperature

“…However, the temperature measured during RF energy application may be affected by catheter orientation, contact pressure, catheter stability and blood flow, among other factors. [26][27][28][29][30] Therefore, measurements of the catheter-tissue interface temperature do not necessarily represent the myocardial temperature near the slow pathway.…”